1. Field of the Invention
The invention generally relates to the production of fatty acids such as eicosapentaenoic acid (EPA) from crude glycerol. In particular, the invention provides methods and compositions for the preparation of fatty acids such as EPA from crude glycerol using the fungus (oomycete) Pythium. 
2. Background of the Invention
Eicosapentaenoic acid (EPA, C20:5, n-3) is an important fatty acid in the omega-3 family based on its medically established therapeutic capabilities against cardiovascular diseases, cancers, schizophrenia, and Alzheimer's disease (Simopoulos, A. P. Essential fatty acids in health and chronic disease. Am. J. Clin. Nutr. 1999, 70, 560S-569S; Ursin, V. M. Modification of plant lipids for human health: development of functional land-based omega-3 fatty acids. J. Nutr. 2003, 133, 4271-4274). However, a microbial-based EPA source has not been commercially available. Fish oil as the main source of EPA has several limitations such as undesirable taste and odor, heavy metal contamination, and potential shortage due to overfishing, variation in seasonal availability of source fish, and cost of production. Thus, it would be highly beneficial to identify and develop new sources to produce EPA.
Biodiesel as an alternative fuel has attracted increasing attention in recent years. In the United States, for example, the annual biodiesel production has increased sharply from <100 million gallons prior to 2005 to 700 million gallons in 2008. During the biodiesel production process, crude glycerol is created as a byproduct. In general, for every gallon of biodiesel produced, 0.3 kg of glycerol is produced. With biodiesel production growing exponentially, the market is being flooded with crude glycerol. Some uses for this crude product have been developed (e.g. combustion, composting, anaerobic digestion, or feeding for various animals such as pigs and chickens). Converting crude glycerol into value-added products through thermochemical or biological methods is another alternative for utilizing this waste stream. However, the amount of crude glycerol being produced still far exceeds the demand for these uses. Because it is prohibitively expensive to convert and purify the crude glycerol into material that can be used for food, cosmetics, or pharmaceutical industries, biodiesel producers are actively searching for new uses for crude glycerol. There is therefor an ongoing need to discover and develop new methods of using crude glycerol in a constructive manner.